A spinning machine having a drafting frame and spindles of this type is described in EP 0 162 787 B1. The drafting frame of this spinning machine has disk-shaped suction rotors located downstream of the drafting zones and onto which the fiber rovings pass to compact the roving. This compaction is formed at least in part by the sucking of the fibers forming the roving onto a small track of the perforations which are provided in a row on the circumference of the rotor. In some of the embodiments described in this reference, the axis of rotation of the suction rotor is inclined so that the plane of the perforations of the rotor lie in the plane tangent to the normally inclined output roller pair stretching rolls of the drafting frame. Two rovings supplied next to one another from respective paths of the drafting frame can be combined, e.g. to a core yarn, on this suction rotor and, via a false twist spindle, a false twist can be imparted to the yarn which is then wound up into a bobbin.
Because of the location of the suction rotor in this assembly, at least one of the rovings is compelled to travel in an incompletely stabile state, i.e. without twisting, over a relatively long path. In this region the roving can be damaged. For example, its fibers can be entrained in air vortices or pulled apart by spurious air currents. There is also a tendency for the fibers to project outwardly from the roving so that the product has a high degree of hairiness. Furthermore, the long distance which the roving is compelled to travel from the rotor to the spindle or from the drafting frame to the rotor can interfere with the uniformity of the roving. Finally, tension can be applied to the roving by the ring-spinning spindles where the roving lies against the suction rotor so as to be detrimental to the compaction of the roving.